The present invention relates to current-limiting contactor apparatus primarily used in a circuit breaker.
A conventional current-limiting type of contactor apparatus is shown in FIG. 3 by way of example. In the drawing, a movable contactor 3 is pivotally supported at a shaft 4 by a contactor support 2 fixed to a switching shaft 1 and a movable contact 5 is integrally provided at an end portion of the movable contactor 3. The movable contactor 3 is bent in a U-shape and disposed so as to be able to detachably contact with a fixed contact 7 of a fixed contactor 6 which is arranged so that the direction of the current flowing in the fixed contactor 6 is opposite to that of the current flowing in the movable contactor 3. The movable contactor 3 is urged against the fixed contactor 6 by a helical torsion spring 8 mounted on the shaft 4. The magnetic repulsion force F between the contactors 3 and 6 is represented generally by the expression F.varies.(L/S)I.sup.2, where L is the length between the contactors 3 and 6, S is the distance of separation between the movable and fixed contactors 3 and 6, and I is the currentflowing through contactors 3 and 6. Accordingly, in the thus arranged contactor apparatus, as the distance S between the opposed movable and fixed contactors 3 and 6 is made smaller (i.e., to S1 in FIG. 3), and as the length L between the contactors 3 and 6 and the current I flowing through the contactors 3 and 6 are both made larger, the magnetic repulsion force F acting between the contactors 3 and 6 becomes larger.
However, there are disadvantages in the conventional contactor apparatus in that when the movable contactor 3 is separated from the fixed contactor 6, the opposing distance S1 in the initial stage becomes larger as the separation progresses(i.e., to S2 in FIG. 3), so that the magnetic force decreases in proportion to the increase of the opposing distance S1 to lower the breaking speed to thereby lower the current limiting breaking performance. If the opposing length L is made longer as means to compensate the above-mentioned disadvantage, the contactor apparatus per se becomes large in size.